HDU 1251 统计难题

 

http://acm.hdu.edu.cn/showproblem.php?pid=1251

 

解题思路：数据量太大，遍历字典一定超时，所以就直接用字典树做了。

 

#include <stdio.h>#include <string.h>struct trie{trie *child[26];int num;}*root;/*插入单词到字典树中*/void insert(char *str){int i,j,len;trie *curren,*newnode;len = strlen(str);if(str==0)return;curren=root;for (i=0;i<len;i++){if(curren->child[str[i]-'a']!=0){curren=curren->child[str[i]-'a'];curren->num=curren->num+1;}else{newnode = new trie;for (j=0;j<26;j++)newnode->child[j]=0;curren->child[str[i]-'a']=newnode;curren=curren->child[str[i]-'a'];curren->num=1;}}}/*查找前缀单词，返回匹配单词数量*/int find(char *str){int i,j,len;trie *curren;len = strlen(str);if(len==0)return 0;curren=root;for (i=0;i<len;i++){if(curren->child[str[i]-'a']!=0)curren=curren->child[str[i]-'a'];elsereturn 0;}return curren->num;}int main(){int i;char str[11];root=new trie;for (i=0;i<26;i++)root->child[i]=NULL;root->num=2;while (gets(str),strcmp(str,"")!=0)insert(str);while (gets(str)){i=find(str);printf("%d/n",i);}return 0;}